Automatic telephone system.



F. M BRK. AUTOMATIC TELEPHONE SY STBM.- APPLICATION FILBD'AUG. as, 1911.

Patented Mar. 16,1915.

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P. MERK. 7 AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG. 25, 1911. 1,132,107. Patented Mar. 16, 1915.

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F. MERK. AUTOMATIC TELEPHONE SYSTEM. APPLICATION TILED AUG. 25, 191.1.

' Patented Mar. 16, 1915.

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MERK, 0 (EEBZVIANY'. ASSIGIL'QR TO SIEMENS S:

-YE, A. 43., OF BERLIN, ("1E YEANY, A COEPQRATIGN OF GERMANY.

AUTOMATIC I'ELEPHQNE SYSTEM.

ems-mes 3131316., i973;

Application filed August 25, 19111. erial 1%. 6%,877.

To all am "it may concem Be it known that. l, FRIEDRICH Meme, :1 Sub eQt of the German Emoeror, and re- 1 v Q swung. at Charlotte burg, near Berlin, (Tereertain of operation ecanse E: prevent seieo-oi: being set; Yotne connecting co of a broken line or of the trunk o selector removed isfoimits piece foi' em on? many have inventednertain new and useful. pose of repair or lhe like. I an Improvements'in Automatic Telephone 33 5- Another object of my inn W terns, of which the following is a speeificsviii-e at the said repeater relz-iy tion. v i.'selt' kept energized, even (lining My invention relates to automatic tel, sionotf impulses, by a current iiowio phone systems inwhich. tolling connections tile line sending (he impulses for setli. 1

selectors, and which holds closed at e n eontoel, the test line going out-from ilie selector whereby it ineinizoins a hoh'li suit for the relay at the ineomin to line. When en'inlo' x-"ing n much connect the calling line with i selector, I pz'ovidemeans so: the so l. for keeping eloseei the test line ooo'i the ore-selector and thereby keeping selector set. v Further, my system eoi'n'prl ing subscribers lines a metero emteii by a relay at the repeaier, saiel relay being nergizeil sift-ea the connector has been set to the A primary object of my ii'iveiition is s; requireci line and pz'effeifa'oly after lho ozilleel a P ovide weimple and efiicient autonmtio ia le subscriber has one .f-eeordii g o my phone system, particularly one in 'wh oh invention this; rein selectors and counselor opeialie witrmu:v lied in such 7; so'called side switch. lnsteml of th side ii; is Conn are preferably established between the sub scrioers lines by means of a plurality of selector switches and a connector si itch adapted to be set by our; 3; ii'npnlses, calling line-being preferably connected by switching devices, such as prewlmtots, call seekers or the like, with a. free hl'fil} sole/(thorn The invention partieulmly relates to a system in which there is arranged lvetii e n the said pre selectoi' and me seleea set of repeating relays'or a repeater wh the selectors to the operating and switch: 1g

magnets of the seleetors :inii connector.

switches I employ at the selector and eoncan be neotoi' switches of my systeijn role eonio. in i" care being taken that not only the non of both the contacts and the re eon m,

the consumption of em. ent me during: the CMEHGCUOIE small.

according to my invention 1 eom'ieel inoo the incoming end of the test.

switchappertaining thereio x office, and the i'epeoter oonnmitw line, which from one selector to the nextand from the last selector to the connector, :1 eels} which loading to a first seleeioz ewi is maintained energized L a holnwg con shone a first, Eli rent flowing over the test line 'xolh F25 lotion of the adjustment of the seleefioi' oi hector and also elmix'ig the eo'i'itimiaizee of The drawings ilmstmte the connection. This relay oonfnols the tion of the system; the cm leasing circuit of its selector or connector. meel'muicnily arranged simi? which is led Yer lil'eali eontoot at th known switches .lhe z'ziovohie poi annatui'e of the relay, in such manner the represented in the r the release takes place at the outgoing ml ception of the COfibfiCC' arms o of the test line when the holding Clil'i :l, switches which are in each (3 3-2; flowing over the test line intei mpteil Ev in connection with :1 line .o ilze new allowiiu a current to flow over the tesl: li switch.

in the stated manner when one selector is When i'liesuhsevioei E0. 1234? :emow connected with the next, or the lost sele'rtoi' his felephone and Wishes to be conneelx.

with the COImeCt-GY, I obtain :1 system very ioll 5;

'iiih' she suhseribei K 3 61899 the circuit is closed:-ground, "battery G, coil 1 of the call relay R, contact 2. branch (2 of the line contact 3, induction coil 4, microphone 5, branch 3; of the line, contact 6, coil 7 or" the relay R, ground. The relay R is energized and switches the rotary mag net I) of the pie-selector at the contact 8 into an interrupter circuit, so that the contact arms 9, 10, 11 are rotated a step at a time. This breaks a circuit from battery G, contact 18, test relay T, side switch contact 12, test line leading to the connectors, as shown at the preselector of the line 67890 ,(see contact 87.) A connector testing a line interrupted at .12- will not find con nection to the battery which is necessary the followii to energize the connector test relay P over the test contact 83. The opening of contact 12 therefore guards a connection against calls over connectors. In addition, at the first step contact 18 is opened and contact 1? closed. The relay R connects the arm 11 through contact 13 with the battery and ground through the meter Z and the low and high resistance coils of the relay T. As soon the arm 11 contacts with a free line, the following testing circuit is formed :-ground. battery G, con tact 13, relay T, meter Z co'ntaot arm 11, line 0 contacts 14}, 15, relay C, end contact 10 of the switch shaft of the first selector, ground. The relay T in the pro-selector is actuated an disconnects the call relay R and with it the rotary magnet D at the contacts 2 and 6, The pro-selector therefore remains stationary at the sought line a, b 0. Further, the relay T short circuits its high resistance coil atthe contact 16, whereby the sought line a, b, c is occupied, and the above-mentioned test ing circuit, after opening the contact 18, continues to remain as a holding circuit over the ground, battery G, contacts 17, 16, low resistance'coil of relay T, meter Z, contact 11 and so on. The current is so Weak that the meter is not actuated. Lastly, the relay 'T connects the calling subscriber over the contacts 19 and 20, the contact arms 9 and 10 and the lines a and F) with the repeating relays A, X and B The following circuit is at once 1'orn1ed:-

ground. battery G, relay A, one coil of relay X, branch 5!, subscribers station. branch Z). the second coil of relay X. relay ll to ground. The relays A and B are actuated but not the re X at first, because this is dill'erentially wound.

By means of contact bridges o cr contz. stilhclosed:

ion, this reluy cl -gound. battery G, o. relay V, contact 24, ground. The relay V closes a contact 25 in parallel with contact and opens contact- I-t whereby the low resistance coil of contact co.

the relay C is connected into the above mentioned holding circuit of the relay -T of the pro-selector and of the relay C of the first selector. T he relay C is energized, opensthe contacts 15 tact connects its high resistance coil in parallel with the relay C of the first selector. The two coils of the relay C are so connected that their actions support one another. The relay V, in addition, connects the meter relay Zr on the one hand by way of its contact 65 to ground, and on the other hand by way of the contact 64 to the line b,. This line 'b', is separated from the line 6,, and the line a, from the line a, by condensers 166 and 167, respectively. Now when the calling subscriber brings his numbered dial out of its rest position ih order first to select the numeral 6, the contacts 126 and 27 are closed, whereby the lines a and Z) are grounded. The differ-ential relay X is hereby actuated and closes the following circuit ground, battery, re sistance 28, contact 29, point 30 of the righthand coil of the relay .X and from here firstly by Way of the relay B to ground, and secondly over the right-hand coil of the relay X, line 6 contact arm 10, contact 20, line 6, contact 26, contact 27 and ground. This current in the line I) and?) flows in a direction opposite to the previous direction, so that the actions of the currents in the two coils of relay X now aid one another. This relay disconnects the meter relay Zr from the line b, atthe contact 61- and then closes a circuit from ground by way of the battery G, contact 31, line 6,, contact 322, relay B in the first selector to ground.

When the subscriber allows his dial to run back from number 6, the circuit is broken six times in succession at contact 3, the repeating relay A becomes currentless each time and on its part each time closes a circuit from ground and battery G over the contacts and 34, line 01,, contact 35, relay A to ground. The relay A imparts the impulse by means of contact 36 to the lifting magnet H of the first selector. The switch shaft with the contact arms 37; 38, 39 is hereby lifted six steps. contact It opens, but this brings about no changes as the relay C has previously closed a parallel contact l0; in addition, the head contact is is closed at the first step, whereby the connection into circuit of the rotary magnet D is prepared. W hen the dial has again reached its rest position the original state is again brought about in the subscribers line, the relay X'becoming currentless and releasing its arniatures. Simultaneously, the relay B in the first selector also becomescurrentless and connects the rotary magnet D into the following circuit:-gr0und, battery G, interrupter U, rotary magnet D, contacts 41, .42, 43, head and 23, and at conresistance coils of the testing relay P, contact arm 39, conductor 0 relay C in the second selector, head contact In, battery G, ground. The relay P is energized, disconnects the rotary magnet D at contact 42, so that the selector remains stationary at the sought line a 6, c and short-circuits the high resistance coil of relay P over ground, head contact 10 contacts 4-3 and 45, whereby the sought line is locked. The current for relay P remains during the continuance of the connection. In addition, the relay P disconnects the relays B and A from the lines a, b at the contacts 32 and 35, respectively, and 'connectsthe relays A and B of the second selector over the contacts 46 and 47 into the circuit of the contact arms 37 and 38, lines a and b and contacts 48, 49. The relay; C of the second selector connects, among others, the contact 50 in parallel with the head contact is as in the first selector.

The connection and arrangement of the second selector is the same as in the first selector except that the relay C in the second selector is connected to the battery, whereas in the first selector it is directly grounded. Accordingly, the second selector is set in the same manner as the first selector. Vhen the subscriber rotates his dial a second time to the numeral 7, the differential relay X is again energized and with it the relay B of the second selector while the dial rotates. Then when the dial returns and the relay A receives impulses, these are transferred to the relay A of the second selector and hereby to the lifting magnet H. The shaft of the second selector is consequently lifted seven steps. At the first step the head contact I61 is opened and the head contact k closed. After the dial has run down the relay X and the relay B of the second selector are de'energized, and the rotary magnet D of the second selector receives impulses, whereby the contact arms 51, 52, 53 are rotated. \Vhen a free line is contacted the following circuit is established ground. contact 54:, high and low resistance coils of the testing relay P, contact arm 53, conductor 0 relay C in the third selector, the releasing magnet M, battery G, ground. The releasing magnet is not actuated as the current is too weak. The testing relay'P in the second selector is actuated, disconnects the relays A, B, and the rotary magnet D and short-circuits its high resistance winding exactly as in the first selector. The 3 current for the relays P and C remains during the continuance of the connection as in the first selector. After the relay P in' the second selector has been actuated the lines of, b are connected over the contacts 55, 56,

contact arms 51, lines a b and contacts 57,

58 with the relays A and B in the third selector.

The third selector could be connected just as the second selector as it operates in the same manner; the connection of the relay C and the releasing magnet M, however, is preferably modified for the purpose of limiting the number of contacts. The subscribers dial is now rotated a third time to the numeral '8, whereupon the relay X and the relay B in the third selector are actuated. \Vhen the dial returns the repeating relay A receives eight impulses which are transferred in known manner in the third selector to the relay A and the lifting magnet H. The switch shaft of the third selector is lifted eight steps. At the first step the head contact it closes, the other head contact being omitted. This closure of the contact is at first has no influence on the circuit of the relays C and M as the contact 59 of the relay C has been previously opened. \Vhen the dial has run down and the relay X and the relay B in the third selector are deenergized, the rotary magnet D receives impulses from the interrupter U until, on contacting with a free line a, b, c, the following circuit is established :ground, contact 60, high and low resistance coils of the testing relay P, contact arm 63, conductor 0, head contact 7: in the connector, relay C, battery G and ground. The testing relay P and the relay C in the connectorare actuated and remain energized during the con- C in the connector is energized the auxiliary relay E in the connector is energized in the following circuit :ground, head contact k", contacts 70, 71, relay E, battery G, ground. This relay E closes a contact 72 parallel with the head contact 10 so that the relay E remains energized even after the contact 7: has been opened when the switch shaft rises. The relay Ev connects the relay A by the contact 73 with the ground. Now when the subscriber rotates his dial to number 9, the relay X is actuated during 'the'continuance of the rotation of the dial and also the relay B in the connector. \Vhenfthe dial returns the repeating relay A receives nine impulses which are transferred in the connectorto the relay A and to the lifting magnet H. The circuit for this magnet is ground, contacts 74, 75, magnet H, battery 25..- the relay A.- As the relay F has steps. At the first step the contact is: is opened but thc'relay C holds itself connected incircuit' by way of the contact 76. In ad dition, the contact 10 is opened and the con tact k closcdat the first step. Therefore, after the dial'has' run down and the relays X and B are currentless, the following cuit is closed z-ground, head contact a contacts 77, 78, auxiliary relay F, battery G, ground. The auxiliary relay F is actuated and holds itself energized by means of the contact 79 even after the contact 77 has been opened. The last rotation of the dial by the subscriber to the cipher 0 now takes p ace, whereupon the relay X and the relay Bin the connector are actuated during the continuance of the rotation of the dial. As the contact 79 is closed the relay B now en- =ergizes the auxiliary relay G in the following circuit :-ground,-contacts 79, 84, auxiliary relay G, battery G, ground. All the three auxiliary relays E, F and G are now energized. On the dial returning, the repea'ting relay A receives ten impulses which are transferred inthe connector to been energized in the meantime, the relay A new transfers its impulses to the rotary magnet- D, instead of to the lifting magnet H, in the following circuit:'ground, contacts 7a, 80, rotary magnet D, battery G, ground. The contact arms 81, 82, 83 are rotated ten steps and thereby connected with the desired sub-. scribers line. When the relay X and the .relay B in the connector become currentless at the end of the rotation of the dial, for the purpose" of testing the required subscribefs line the following circuit is made :-contact arm. 83', ow and high resistance coils of relay P, contacts 85, 86, ground. When the required 'subscribers 'line is free current flows in the following circuit :ground, contacts 86, 85, high and low "resistance coils of relay P, contact arm 83,-conductor 0, contact 87 in the preselector of the called subscriber, meter Z, low and high resistance coils of relay T, contactSS, battery G, ground. The relay P in the connector and the relay T in the pre-selector of the called subscriber (but not the meter Z) are actu' ated and remain energized during the con tinuance of the entire connection. The relay T separates the call relay R from the subscribers line a, b at the contacts 89, 90. a By means of thecontacts 91, the relay P in the pro-connector bridges supervisory relay Y over the battery G between the contact arms 81 and 82. The relay Y is, howeyer, not at present actuated, because a condenser is connected in circuit at the subscribers station. The relay P closes a second circuit over the contacts 9236i to ground for the already energized 113 so that this relay remains energized when the other path, 1'. e. ground and contacts 79,

13 has completely fallen down,

the same is energized each The relay E also disconnects the relay A at contact 73, so that the longer actuate the connector by rotating his dial. By means of the contact 78 the relay E also breaks the circuit for the slow-actsubscriber can no ing relay F. So long as this relay F retains its armature the call-bell relay L is energized in the following circuit :ground, battery G, relay L, contacts 96, 97, 98, ground. The relay L is therefore energized as long as the contact 98 is closed and by tilting over the first call-signal to the desired subscriber. hen the armature of the slow-acting relay the call-bell relay L is connected at contact 101 to a switching device 102 which periodically closes the circuit for this relay L, whereby time and sends additional call-signals. Each time the relay L is energized it "sends to the calling sub scriber a disengaged signal along the following circuit:ground, coil 118 of the buzzer, contact 119, condenser 110, contact 111, relay A, contact 68, line a to the calling subscriber, line 6, contact 69, relay B, ground. After the armature of the relay F has fallen down, this relay sl'iort-circuits the high reeistance coil of the relay P by its contact 117, so that the desired subscribers line is locked. iVhen the called subscriber answers by removing his energized and by means of its contacts 68, 69 disconnects the relays A, B and closes the talking circuit at The relay Y also interrupts at the contact 9% the current for the relay G, so that the latter is deenergized and disconnects the callbell relay L at the contact 96. Further, the relay Y closes the contact 116. so that the current for the relays P and T now flows over the contacts 117 and 116 instead of over the contact 86. At this moment metering takes place. A part of the current flowing by way of ground, battery G, relay Y, contacts 100 and 92 flows by way of the contact 10%, line 6, contact arm 62, contact 67, line. 0, contact arm 52, contact 56, line 6 contact arm 38, Contact 47, line (2}, contact 64 meter relay Zr, contact 65, to ground. The relay Z1 is energized and by closing the con tact 105 it increases the holding current. flowing since the beginning over the relay T and meter Z in such manner that the meter Z is now actuated. In addition, the relay Zr breaks at the contactQt the circuit, closed formerly, for the slow acting levers 99, 100 sends thereceiver, the relay Y is the contacts 103, 101.

commenced. The microphone of the caliihg therefore slowly ""ereirooh the contacis the contact 2% has been ell lie-misc the contacts 23 and are open. The low re sistance coil of relay C kept energized. however. as before. by way of 26 and the high. resisoance coil 0 After the meter relay Zr has b connected the conversation can be at a station is fed by way of the relays A". B and X, and the microphone of the called station by way of the relay Y in the connector. The two feeding circuits are. separated from one another by the con- ClERSTS GG'and 6i.

\Vhen the required subscribers line is busy, afterthe contact has been closed the testing relay P is not actuated and there fore the relay Y is not connected the con tacts 91 and 92 to the reouired scribers line. Further, "the call-rclay L is not con nected into circuit at contact 93'. l'iasiiy. the holding circuit for the relay G is not closQ'tl at. the contact 93. TllEIGfOI-Q. when the relay B becomes currei'itless and -the contact iii-flopens. the armaturcs of .all three auxiliary relays E. F and (i fall back in turn into the rest position. The relay F.- bceaks the circuit for relay F at couiact '59. and relay F the c rcuit for relay G at contact 79. The calling subscriber now receives a lasting buzzer current which flows from ground by Way of the coil 97 of the. buzzer. contacts 108, 109, condenser 11C. contact. 111. relay A. contact 68, branch a to the suiscriher and by way of the branch back bv way of con'i'ac relay l3 and grorn-cl. \Vhen the sitl'iscriher hears this engaged signal he should replace his receiver, whereupon the connection done away with as described hereinafter. It is to be noted that. after the armature i of the relay G has fallen. the testing relay P is cut out at contact 85. so that this relay P cannot be subsequently energized again if the called line should in the meantime bccome free. In addition, in this event no metering takes place as the circuit for the meter relay Z-r is not closed at contact 10%.

"When the calling sub criber replaces his receiver after the conversation. the relays A and- B become curreotless. By opening the contact {contact pen the relay i 'ii the first se G l-cilli'lfiifi 1?. 16, low resistance coil of relay T. meter Z. contact arm 11. contacts h -h rcsisiance coil of relay C ire to the high 1 tance of i". ii weal-(coed to such an extent that the rela 'l' releases its armature. whereupon the c ii'. for relay C and role l automatically broken at Contact Tlv relay C therefore becomes currcntiess togeth with relay T. Thereby the circuit for rotary n'iagnei D of the prescect 1 is cl secl again as follows: ground, i vrru i'zcr U. rotary inagn'e D, contact l'ii, cc itact 1?. battery G ground. As soon as the contact 7 arms oi the thus rotated presereach the normal posi ens, and c ntact 18 of the rotary magnet D is therefore broken 1?. The pro-selector now returns in known. manner into its zero position.

.Vhen the armature of the relay C in the iirst selector is released the releasing magnet M is. connected into the following circuits-ground. end coiitact k contact l3, nia 'nct 3- battery G, ground. Thismagnet returns the switch shaft in known manner into its rest position. The circuit is ai'atoiiiatically finally broken at the contact if. while at thccontact It" the relay C is connected with the ground. whereby the first selector is again accessibe for further calls.

ion. contact 17 closes. The circuit S.1C I The relay 1 opens the contacts .3. 4-6 and -l'Z.'so that the contact arms are isolated when the switch shaft hillsback.

Going to the relay C becom ng currentless the second selector is released in the some manner as in the selector. The current for the relay P is interrupted by the second s lecti'ir and toot f r the vylay C of the third .ector. The relay C of tie third selector brings about the release of the third selector and the disconnection of the relav P and of the relay C in the connector. The preselector and all the selectors are now released. The connector is released togetherwith the s .lectors only when the relay Y has not been energized. i. e. in the case of a line being husy or when the called subscriber has not announced himself. ll the relay Y has been actuated the circuit:----, :round. battery G. releasing: magnet M. contacts'lll, 115, head contact L ground. remains open contact 115 until the relay Y becomes currentless. 6. until the called subscriber has also reolacecl his receiver. Wl'ien. rcvcrsely, the called subscriber replaces his rcceii'er before the calling: subscriber. the connector likewise not released. because the rcleasing circuit. lup open at contactlfi by the relay 'ii suhscriherbe em 3 re iilecii'igf his re opened, when the-relay Y becomes currentless, at the contacts 103 and 104, and the curduring the conversation for rent flowing illierelays P and T is broken at the contact My invention is not limited to the illustrated embodiment. Particularly, it is not necessary that the impulses for setting the selectors and the connector proceed from one subscribersstation. On the contrary, the invention can also be employed in semiautomatic systems in which operators send the impulses.

. I claim 1. In an automatic telephone exchange system, the combination of subscribers lines, selector and connector switches adapted to e set by current impulses for establishing a connection between the said lines, devices for connecting a callingline with a free first selector, a repeater located between the said devices and the first selector, devices at the said repeater for, holding'and breaking the connection, lines between the said switches, a relay located at the incoming end of the test line of each switch and energized during the connection by a current over the test line, and means for interrupting the said current at the outgoing end of each test line.

2. In an automatic telephone exchange system, the combination subscribers lines, selector and connector switches adapted to 6 set by current impulses for establishing a connection bet een the said lines, devices for-connecting a calling line with a free first selector, a repeater located between the said derices and the first selector. de ices at the said repeater fofholding and brealc .lng the connection,-test lines between the said switches, a relay located at the incoming' and of the test line 01 each switch and energized during the conned-ion by a current over the testlin'e, and n cans for interrupting the said current at the outgoing end of each test line in every stage of the connection.

3. In an automatic telephone exchange Systenn the combination of subscribers" lines. selector and connector switches adanted to be set by current impulses for establishin5 a connection between the said lines. devices for connecting a calling line with a free first selector, a repeater located between the said devices and the first selector, devices at the said repeater for holding and breaking the connection. test lines between each two successiveswitches. a relaf, at each end of each test line. a holding circuit for the relays closed over the test line during the connec tion, and means for breaking the said hold- 511g circuit at the selector switch at the outgoing end of the test line.

A 4. In an automatic tcleph systennthe coinbinat' selector and connector switches adapted to be set by current impulses for establishing a connection between the said lines. devices for connecting a calling line with a free first selector. a reneater located between the said dc and the first selector and l'iavingline )ermanently bridged over the talking ii 1 iices at the said repeater for holding and breaking the connection, test lines between each two successive switches, a relay at each end of each test line, a, holding circuit for the relars of said test line, closed over the test line during the connection, and means for breaking the said holding circuit at the selector switch at the outgoing end of the test line: means for keeping energized one of the said line relays during the impulses and i during the connection, and means for keeping closed over the attracted armature of the energized line relay the holding circuit for the outgoing test line.

In an automatic telephone exchange system, the combination of subscribers lines, preselcctor, selector and connector switches adapted to be set by current impulses for establishing a connection between the said lines, a preselector for connecting a calling line with a free first selector, a repeater lo cated between the said preseiector and the first selector, and having line relays permanently bridged over the talking line, vices at the said repeater for holding and breaking the connection, test lines between each two successive sWi hes, a reniy at each end of each test line. a holdin circuit for said relays of the test line, closed over the test line during the connection. and means for breaking the said holding circuit at the selector switch at the outgoing end of the tc t line; means for-keeping ener ized one oi the said linerelavs during the impnls and durina' the connection, and means keeping closed over the attracted armatni' relay the holding onof the energized line .cuits oftle test line going out from tl e repeater and. of the test line coming in from the pre-selector.

6. in automatic telephone exchange system comprising in combination, subscribers lines, selector and connector switches adapted to he set hv current. ininulses for establishing a connection beti. zen the said lines, a set of repcatin efrelaysh-i 'ingline relays permanentl bridged o er the talking lines. test lines between each two successive switches, a relay at each end of each test line and energized by a current over the test line. and means at the relay at the incoming end of the testline for interrupting the current over the test line g oin-if out from its switch to the successive switch.

7. A telephone s hination, subsc .oers lines, auirnnatic switches adapted to he set by impulses for stablishing a connection bet een suhscrib em, comprising in comens lines, a set of repeating relays having,

line relays pernianentli bride-ed ore? the talking! lines. test lines between each two successive automatic switches. a relay lo- 5 c'ate'd at each end of eacn testline and energized by a current over the test line and over a'inak'e contact of the relay at the incoming end ofthe test line.

8. An automatic telephone exchange system, comprising in combination, subscribers lines, automatic switches adapted to be set by impulses for establishing a connection between subscribers lines, a set of repeating relays haring line relays permane'ntl bridged over the talking lines, test lines between each two successive automatic switches, a relay at each end of the test lines energized by a current orer the test line, means at the relay at theincoming end of the test line for interrupting the currentover the test'line going out from its switch to the successive switch, and means at the incoming" end of the test line for keeping it interrupted until the switch atthis end has returned (0 its normal position.

9. A telephone system, comprising in combination. telephone lines, pie-selector, st

and connector switches, a set of rere means at the repeating re- .rng and breaking the connect linesbctween each two successive r a relay located at each end of the test line of each switch and energizedby a current over the test line, means for interrupting said current over. the test line ateach stage of the connection, two operating magnets and one releasing magnet at'each lector switch, a circuit for one of the i Qiug magnets over a make contact said relay at the incoming end of the of the test line, and a circuit for the releasing magnet oiera break contact of the said relay.

. An automatic telephone systcm, comp'ri n in combination, subscribers lines, pro-selector, selector and connector switches, a repeater, one relay of said repeater having ieans for senarating the calling and the called. halves of the connection during the impulses, and means for energizing the said relay before the impulses sta t and until the impulses stop.

11. An automatic telephone system, cemprising in combination, subscribers lines, pro-selector, selector and connector switches,

a repeater, a diil'crcntial relay at said repeater having means for separating, the calling and the called halves of the connection during the impulses. said differential relay having one cell connected to each branch of the calling line, and means for grounding one branch of the calling line ocf 'n-e start ing the impulses and keeping it grounded until the impulses stop.

19. An automatic telephone exchange system, comprising in combination, a calling and a called subscribers line. a connector switch for complet ng the talking connection between the said lines. selector switches for connecting the call ng line with the connector switch, a testline from the last selector switch ,to the connector switch. a relay at the connector in the test line, a holding circuit'for the said relav. means at the last selector switch for breaking the said hold-- ing circuit. a test line between the connector switch and the called line, a te t relay at the connector for testing the called line, a holding circuit for the test relav over the test line of the called line found to be free. one/rating magnets and a releasing m gnet at theconnector, relavs at the connector at the talking lines coming from the last selector, a suner isoryrelay at the connector for the called line, a slow-acting relay and two switching! relavs at the connector, holding. circuits for these latter. three relavs. means at the connector for energizing the s ow-act ngflrelar at the commencement of the unit imnulses and dei ncrgizing the same at the te m nat on thercoil means at the con- 'nector fo closing! the hold ng circuit of the one si' itehinq rclav when the conn ctor is occup ed and breaking the same at the term nat on of the impulses for the'onerating magnets of the conn c or. and me ns at the connector for estab ish ng the holding circuit for the second switc iina relav at the commencement of the last series of im ulses and breaking the same scr ber answers.

Tn tcst monv whereof I sig'n mv name to th s specification in the presence of two witnesses.

HENRY Hasrnn, ARTHUR Scnnornnn.

when the called sub-- 

